Results 1 to 9 of 9
  1. #1
    RC Qualifier
    Join Date
    Mar 2012
    Location
    Los Angeles / South Bay
    Posts
    445

    What would happen if I run 6 cell NIMHs with MM?

    I have a pair of matching 6 cell 7.2v nimhs that I like to use along with my Lipos. Currently the nimhs sit unused most of the time (they're 5000mah, fairly new condition and I used them for my boats) my questions are:

    Will they be severely damaged if I run them in series thru the Mamba Monster system or will they be ok if I go easy on the throttle?

    Will the ESC auto detect the Nimh because I didn't see it in the Driver's Ed guide, can I just plug them in and run, will it damage the ESC etc...?

  2. #2
    RC Turnbuckle Jr. mike-susieq1's Avatar
    Join Date
    Nov 2010
    Location
    California
    Posts
    4,840
    i've heard it will damage the esc running nimh's and being that they are only going to be added up to 12cells. even the 14cell total the 2 7cell 8.4v nimhs come with it are not suited able for running on the MMM.
    DEU 8:18 ESV

  3. #3
    RC Qualifier
    Join Date
    Mar 2011
    Posts
    661
    the batteries may die and the esc could have a "brown out" and destroy its self.

    the nimh packs do not deliver the required amperage for most brushless systems.

  4. #4
    RC Turnbuckle Jr. 87 GN's Avatar
    Join Date
    Mar 2010
    Location
    kansas
    Posts
    7,820
    NiMH are ok sort of... if you keep the stock gearing & take it easy on the throttle & stay off the brakes. It is the ripple current that is hard on the ESC.........
    Would you go flip my truck back over??

  5. #5
    RC Champion
    Join Date
    Aug 2012
    Location
    Central NJ
    Posts
    1,245
    The nimhs will run, just dont expect a lot of power or for them to last very long. 7 cell nimhs is what comes with the ERBE from the factory. Ive run a MMM with a 2650 in a slash 4x4 on 3s for quite a few packs with no problems at all so voltage wont be your problem. You just wont have the kick of the lipos.
    DC is DC no ripple involved. Ripple current is the effect caused by producing DC from AC as in a crappy charger is not good for your batteries and why those who are really into making their packs last as long as possible use DC chargers. If you look at it on an Oscope you can see AC voltage riding on the DC waveform. The large capaitors on your ESC are DC capacitors designed to absorb AC ripple produced by the switching action of the ESC they are keeping it from the motor where the ripple will be absorbed and dissipated as heat in the windings. Power quality and harmonics 101.

    Keep in mind that nimhs have been run in ESCs for far longer than LIPOs.

  6. #6
    RC Qualifier
    Join Date
    Aug 2011
    Location
    delaware
    Posts
    937
    Quote Originally Posted by JustinThyme View Post
    The nimhs will run, just dont expect a lot of power or for them to last very long. 7 cell nimhs is what comes with the ERBE from the factory. Ive run a MMM with a 2650 in a slash 4x4 on 3s for quite a few packs with no problems at all so voltage wont be your problem. You just wont have the kick of the lipos.
    DC is DC no ripple involved. Ripple current is the effect caused by producing DC from AC as in a crappy charger is not good for your batteries and why those who are really into making their packs last as long as possible use DC chargers. If you look at it on an Oscope you can see AC voltage riding on the DC waveform. The large capaitors on your ESC are DC capacitors designed to absorb AC ripple produced by the switching action of the ESC they are keeping it from the motor where the ripple will be absorbed and dissipated as heat in the windings. Power quality and harmonics 101.

    Keep in mind that nimhs have been run in ESCs for far longer than LIPOs.
    trust me this guy know electricty past that all bets are off just kidding justin

  7. #7
    RC Turnbuckle Jr. mike-susieq1's Avatar
    Join Date
    Nov 2010
    Location
    California
    Posts
    4,840
    newer esc's are being designed to run more on lipos since they provide better ampage through the pack or packs when running without that sudden drop at the end.
    DEU 8:18 ESV

  8. #8
    RC Champion
    Join Date
    Aug 2012
    Location
    Central NJ
    Posts
    1,245
    Quote Originally Posted by 4sdash View Post
    trust me this guy know electricty past that all bets are off just kidding justin
    LOL Dash

    One thing I did forget that popped in my head while I was going to sleep last night. Yeah I know, get a life right when you think about electronics going to sleep...

    To run the 6 cell packs you will have to connect to the MMM with castle link and set the battery type or it wont run correctly or if at all. By default all castle ESCs are set to auto lipo detect. I was pulling my hair out on the first MMP I got and went to run it on a 7cell nimh pack and on a full charge it would run for just a few seconds then quit. It was detecting it as a 3s Lipo and shutting down as soon as the pack voltage dropped to 9.6V. The 6 cell may run with the ESC detecting it as a 2s lipo.

    Mike is right though. Newer ESCs, particularly brushless ones, are designed to run Lipos. There is a hidden reason behind this that the novice is not aware of. Its cheaper! Lipos provide a farily constant voltage that negates the need for a DC to DC converter or as us electronics geeks call it a "chopper". The chopper acts a a preamp and converts the input power and regulates a constant voltage to the switching amplifiers that feed the motor. Well if your voltage is fairly constant you dont need a chopper circuit.

  9. #9
    RC Qualifier
    Join Date
    Mar 2012
    Location
    Los Angeles / South Bay
    Posts
    445
    Wow, lots of invaluable info here my nimh's staying on the shelf... a good Turkey day to all

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •